Senior FullStack Developer

This position is listed on behalf of a partner company, who manages all applications and next steps. Our partner is looking for a Senior Full Stack Developer based in Poland. Join an innovative Web3 technology environment developing advanced market intelligence solutions and next-generation decentralized trading infrastructure. As a Senior Full Stack Developer, you will take ownership of architecture and implementation across frontend applications, backend services, and blockchain integrations. You will help build sophisticated trading tools that process hundreds of real-time data streams, transforming on-chain activity and market intelligence into actionable insights. Working with a highly experienced engineering team, you will design scalable, secure, and reliable systems while solving complex technical challenges across decentralized ecosystems. This role offers significant autonomy, broad technical responsibility, and the opportunity to influence core product architecture from design through production deployment. It is an ideal opportunity for an experienced engineer who thrives in a fast-paced startup environment and is passionate about building impactful Web3 products. Accountabilities: Lead end-to-end full stack development across React-based user interfaces, Node.js backend services, and Web3 integrations. Design, develop, and scale decentralized applications that integrate blockchain wallets, decentralized finance (DeFi) protocols, and on-chain data sources. Integrate Web3 libraries, software development kits, third-party packages, and APIs into robust, secure, and reliable product workflows. Architect and implement systems that meet demanding requirements for performance, scalability, security, and interoperability across decentralized ecosystems. Develop and optimize infrastructure capable of processing high volumes of real-time market information, blockchain activity, and other data streams. Take ownership of the entire software development lifecycle, from technical design and implementation through deployment, monitoring, and production support. Investigate complex production issues, identify root causes, and implement improvements that strengthen system reliability and operational performance. Collaborate with experienced engineers on architectural decisions, technical strategy, and research into emerging technologies relevant to Web3 and decentralized markets. Contribute to the development of advanced trading and market intelligence products, helping transform complex data into intuitive, high-performance user experiences. Maintain high engineering standards through thoughtful technical decisions, quality-focused implementation, and continuous improvement of development practices. Requirements: At least 10 years of professional software development experience, with a strong background in designing, building, and maintaining production-grade applications. A minimum of 3 years of full stack development experience with a substantial focus on Web3 technologies and blockchain-based applications. Strong proficiency in TypeScript, React, and Node.js, with the ability to develop and maintain complex frontend and backend systems. Demonstrated experience delivering Web3 applications or integrations to production environments. Hands-on experience integrating blockchain wallets, DeFi protocols, on-chain data sources, and third-party Web3 libraries, packages, or APIs. Proven experience designing and scaling data-intensive systems, particularly those involving real-time processing and high-volume information flows. Strong architectural judgment and a practical understanding of system performance, security, scalability, and reliability. Ability to troubleshoot complex technical issues, make independent engineering decisions, and take responsibility for production outcomes. Excellent problem-solving skills, with the ability to balance rapid delivery against long-term maintainability and technical quality. Fluent English communication skills, with the ability to collaborate effectively with experienced engineers in a distributed environment. A high degree of autonomy, accountability, and initiative, along with the ability to manage broad responsibilities in a fast-moving startup. Comfort working in a demanding, execution-focused environment where engineers are expected to take ownership and deliver results with limited supervision. Experience with multi-chain development, particularly across Ethereum and Solana, is an advantage. Familiarity with Prisma, Zod, tRPC, and Fastify is considered a plus. Benefits: Fully remote work: Work remotely from Poland with flexible working hours. Competitive compensation: Annual salary of up to USD 90,000, depending on experience and qualifications. Technical ownership: Significant autonomy in shaping architecture, making engineering decisions, and delivering core product capabilities. Experienced colleagues: Collaborate with a highly skilled, senior-level engineering team in a direct and execution-focused environment. Web3 innovation: Contribute to advanced decentralized applications, market intelligence infrastructure, and next-generation trading technologies. End-to-end responsibility: Own projects from initial design through implementation, deployment, and ongoing production support. Professional growth: Expand your expertise in blockchain integrations, real-time data infrastructure, decentralized finance, and scalable full stack engineering. Flexible collaboration: Benefit from a remote-first working model with a focus on meaningful output, technical excellence, and efficient communication.